Environmental Sensors

TinyTX3

For many years I used a serial port adapter and two DS1920 temperature sensor iButtons (one indoors, one outdoors) to log the temperature which was graphed using gnuplot. Some experimentation a few years ago with making a cheap wireless temperature sensor led to a bit more than I intended at the time and the TinyTX board that I designed became quite popular. You will find more info and links to code for the below on the TinyTX page.

The sensors all use the RFM12B radios to transmit the readings which are then received by the Tiny328 connected to my Debian server and fed into Node-RED for distribution via MQTT and to InfluxDB for logging and Grafana for reporting (previously a self hosted installation of Emoncms was used for logging).

Temperature

Every room has a temperature sensor and there is one in the back garden in a 3D printed stephenson screen and one outside at the front under the overhang above the front door.

Most of these are the Dallas DS18B20 sensors but there are a few DHT22 (temperature and humidity), one TPM36 analogue sensor and one BMP085 (temperature and pressure).

The majority are running on my TinyTX boards with a couple using the Tiny328.

Humidity

For humidity readings I use the DHT22 aka AM2302. This is a combined temperature and humidity sensor, I have one of this indoors on a TinyTX, one in the back garden on a Tiny328 and there is also one in the Air Quality Egg.

TinyTX with DHT22

Rain

A tipping bucket rain gauge connected to a TinyTX takes care of rain measurement. This is one of those plastic buckets that come with the cheap weather stations, I picked up it for next to nothing second hand as it didn’t work but just needed the reed switch changing. It does the job but sometimes gets stuck and needs a whack to get it moving again. I also have a rain sensor connected to this.

Tipping Bucket Rain Gauge with TinyTX3

Air Pressure

A BMP085 sensor is fitted to a TinyTX in the hall, this does air pressure and temperature.

Carbon Monoxide (CO)

I’ve got one of the original Air Quality Eggs which takes care of CO and NO2 measurements and also has a DHT22 for temperature and humidity. This is situated outside at the back of the house and uses a E2V MICS 5525 for CO sensing. I wrote a blog post about the Air Quality Egg here in 2013.

Nitrogen Dioxide (NO2)

This is taken care of by the Air Quality Egg using a E2V MICS 2710 sensor.